The present invention relates to a receiving device for receiving a paid broadcast, and more particularly, to a paid broadcast receiving device which can detect whether or not a paid broadcast decoder and receiver are interconnected.
In recent times, as the prevalence of paid broadcast programs is increasing in some European countries, e.g., Germany, Spain and France, there has arisen a need for adding a jack to a video apparatus so that a decoder can be connected thereto for unscrambling the scrambled broadcast signals. In a color television set or VCR for receiving SECAM television broadcasts, a canal+ jack (21 pin scart-jack) can be added so as to connect a canal+ decoder (also known as a "paid broadcast decoder") for receiving the paid broadcast programs.
A canal+ channel system or a canal+ broadcast system is a system which can receive and display a transmitted signal only when a decoder for decoding the scrambled broadcast signal transmitted from a broadcast station is provided, and is a paid broadcast system ordinarily using a radio frequency (RF) signal. The canal+ broadcast system decodes and receives the coded broadcast signal via a canal+ decoder. There are basically two paths for receiving canal+ broadcasts: a television canal+ (TV canal+) and a video cassette recorder canal+ (VCR canal+).
The TV canal+ is a path wherein a scrambled canal+ broadcast received through a television tuner is unscrambled via a canal+ decoder connected to a VCR, with the result being input to the television while the VCR power is off (on standby power). Here, the power provided to the VCR can be classified as "standby" power, "power-on" power, "PB" power for playback, and "REC" power for recording.
On the other hand, the VCR canal+ path is one through which a canal+ broadcast input to a VCR tuner is transmitted to a canal+ decoder for unscrambling the canal+ broadcast signal, with the VCR in the "power-on" state. The unscrambled result is recorded by the VCR while viewed as a general broadcast signal on the television. Alternatively, a path is provided through which a general broadcast signal is recorded by the VCR and the canal+ broadcast received by the television is decoded by the canal+ decoder connected to the VCR with the decoded result being received at the television's AV port via an AV jack for connection to the VCR.
FIG. 1 is a block diagram showing a conventional receiver for receiving a canal+ broadcast signal.
In canal+ broadcast receiving devices such as a VCR 1 and a television 3, a canal+ decoder 2 can be directly connected to either VCR 1 or television 3. Here, canal+ decoder 2 is connected to VCR 1 which also is connected to television 3, thereby enabling reception of the scrambled signal or general broadcast signal. That is, the above-mentioned TV canal+ and VCR canal+ paths have to be satisfied in order to receive a canal+ broadcast, by connecting VCR 1 to both television 3 and canal+ decoder 2.
Referring to FIG. 1, the input of a first tuner 11 of VCR 1 is connected to an antenna (ANT) and its output is connected to the input of a first demodulator 12.
A contact "b" of a first switch SW1 is connected to the output of first demodulator 12, and a contact "c" thereof is connected to the AV input terminal of VCR 1. An output terminal "a" of first switch SW1 is connected to the input of a first amplifier 13 whose output is connected to the video input terminal of canal+ decoder 2. Reference numeral 4 denotes a canal+ jack for connecting VCR 1 to canal+ decoder 2.
Contacts "b," "c," "d" and "e" of a second switch SW2 are connected to the output of first demodulator 12, the AV input terminal, the line input terminal of VCR 1, and the video output terminal of canal+ decoder 2, respectively. An output terminal "a" of second switch SW2 is connected to the input of a first video signal processor 14 whose output is connected to the input terminals of a second amplifier 15 and a recorder/reproducer 17.
Contact "c" of a third switch SW3 is connected to the output of second amplifier 15, and contact "b" thereof is connected to the video output terminal of canal+ decoder 2. An output terminal "a" of third switch SW3 is connected to the AV output terminal of VCR 1 and one input of a modulator 18 whose other input is connected to the output of a power supply 19.
To the above first, second and third switches SW1, SW2 and SW3, a microcomputer 16 provides a canal+ position signal, first and second selection signals, and a VCR/TV mode control signal, respectively. The VCR/TV mode control signal output port of microcomputer 16 is connected to the control terminal of third switch SW3, to the control input of power supply 19 and to the AV control output terminal (AV CTL) of a canal jack 5 via a diode D2. The first and second selection signal output ports are connected to the control terminal of second switch SW2 via third and fourth diodes D3 and D4. The canal+ position output port is connected to the control terminal of first switch SW1. Diodes D5 and D6 are respectively connected between diodes D3 and D4 and the canal+ position output port of microcomputer 16.
The input of a second tuner 31 of television 3 is connected to an RF output terminal 35 of VCR 3 which is connected to the antenna. The input of a second demodulator 32 is connected to the output of second tuner 31, while its output is connected to the AV input terminal of canal jack 5 and to the television signal input contact "c" of a fourth switch SW4, i.e., the VCR/TV mode selection switch. The VCR signal input contact "b" of fourth switch SW4 is connected to the AV output terminal of canal jack 5, and an output terminal "a" thereof is connected to the input of a second video signal processor 33 whose output is connected to a Braun tube 34. The control terminal of fourth switch SW4 is connected to the AV control output terminal of canal jack 5.
Now, the operation of the receiving device shown in FIG. 1 will be explained with reference to the following Table 1.
TABLE 1 ______________________________________ VCR mode general television mode general canal+ canal+ canal+ general broadcast broadcast broadcast broadcast broadcast ______________________________________ CP signal L H H L L AV CTL L H L H L signal SW1 c b b c c contact SW2 b e e c c contact SW3 c c c b b contact SW4 b b b b c contact ______________________________________
Hereinbelow, the five basic conditions of Table 1 will be described.
(1) General broadcast reception in a VCR mode:
As this case is not a canal+ broadcast condition, the canal+ position (CP) signal and the AV control (AV CTL) signal of canal+ decoder 2 are both "low," and the relevant general broadcasting channel is received from the antenna and selected by using first tuner 11 of VCR 1. The received RF broadcast signal is then demodulated into a video signal by first demodulator 12. Since first switch SW1 is connected to contact "c" and second switch SW2 is connected to contact "b," the output of first demodulator 12 is processed in first video signal processor 14. The processed video signal is output to the AV output terminal via third switch SW3 being connected to contact "c" and set for VCR mode or is input to a recorder/reproducer 17 to be recorded. Since fourth switch SW4 is connected to contact "b" (VCR mode), the output of first video signal processor 14 is input to second video signal processor 33 and displayed on Braun tube 34. Accordingly, the general broadcast signal received via an antenna is signal-processed in VCR 1 and output to television 3 via the AV output terminal of canal jack 5, so that the signal can be viewed.
(2) Canal+ broadcast reception in a VCR mode:
First, when the user purchases a VCR and presets the initial broadcast reception channel, a canal+ broadcast channel is set and stored as the canal+ position channel. Then, when the stored canal+ position channel is selected, the canal+ position output port of microcomputer 16 is set "high." Accordingly, when a canal+ broadcast signal is received in the VCR mode, the canal+ position signal goes "high" and the AV control signal of canal+ decoder 2 also goes "high" to set first switch SW1 to contact "b" so that the tuned and demodulated video signal input is provided to the video input terminal of canal+ decoder 2 via first amplifier 13. The scrambled video signal input to canal+ decoder 2 is unscrambled and output to VCR 1 via video output terminal as a normal video signal. With the canal+ position signal set "high," the first and second selection control signals respectively output from microcomputer 16 are both forced "high," which sets second switch SW2 to contact "e." Accordingly, the unscrambled video signal is selected from the video output terminal of canal+ decoder 2 for input to first video signal processor 14 via second switch SW2. The selected and unscrambled canal+ broadcast signal goes through first video signal processor 14 and is output to television 3, similar to the case where the general broadcast signal is received in VCR mode, and is displayed on the television screen or input to recorder/reproducer 17 to be recorded.
(3) General canal+ broadcast reception in a VCR mode:
When a canal+ broadcast signal is received, as explained above (condition 2), first switch SW1 is connected to contact "b" and the received broadcast signal is provided to canal+ decoder 2. However, the scrambling of the input signal remains since the AV control signal of canal+ decoder 2 is "low," and the scrambled canal+ broadcast signal is input to first video signal processor 14 via second switch SW2 which is connected to contact "e" according to the first and second selection signals. The output of first video signal processor 14 is supplied to second video signal processor 33 for display, since third switch SW3 is connected to contact "c" and fourth switch SW4 is connected to contact "b."
(4) Canal+ broadcast reception in a television mode:
Since the canal position signal is "high" only when a canal+ broadcast is received in the VCR mode, in the case of condition 4, the canal position signal is "low" while the AV control signal of canal+ decoder 2 is "high." At this time, since first switch SW1 is connected to contact "c," the video input terminal of canal+ decoder 2 receives the output of second demodulator 32 of television 3. Thus, the broadcast channel selected via VCR 1 is actually a canal+ broadcast channel tuned in second tuner 31 and input to second demodulator 32. This canal+ broadcast signal demodulated by second demodulator 32 and selected by first switch SW 1 is amplified in first amplifier 13 and provided to canal+ decoder 2. Then, the thus-provided canal+ broadcast signal is unscrambled by canal+ decoder 2 and thereby converted to a normal broadcast signal to be supplied to second video signal processor 33 of television 3 via third switch SW3 connected to contact "b" and fourth switch SW4 connected to contact "b" according to the AV control signal output from canal+ decoder 2.
(5) General broadcast reception in a television mode:
The general broadcasting signal received by the antenna in the television mode is tuned and demodulated via second tuner 31 and second demodulator 32 of television 3. The demodulated output is provided directly to second video signal processor 33 for display, since fourth switch SW4 is connected to the television signal input contact "c" according to the VCR/TV mode control signal from microcomputer 16. Here, too, the canal+ position signal and the AV control signal of canal+ decoder 2 are both "low," since there is no canal+ broadcast reception. Also, first, second and third switches SW1, SW2 and SW3 are connected to their contacts "c," "c" and "b," respectively.
Meanwhile, second switch SW2 is connected to contact "d" if the select control signals output from the first and second selection control ports of microcomputer 16 are each "low" so as to select a video signal via the line input terminal of VCR 1. If the first and second select control signals are "low" and "high," respectively, second switch SW2 is connected to contact "b" in order to select a video signal which passes through the first tuner 11 and first demodulator 12 of VCR 1. Further, if these select control signals are "high" and "low," respectively, second switch SW2 is connected to contact "c" so as to select the output of second demodulator 32 input via the AV input terminal of canal jack 5, and if they are "high" and "high," respectively, second switch SW2 is connected to contact "e" so as to select the signal output from video output terminal of canal+ decoder 2.
In addition, a modulator 18 is enabled in the VCR mode and disabled in the television mode depending on the VCR/TV selection mode control signal which is preset by the user. Further, the user can override the operation of third and fourth switches SW3 and SW4 by the setting of VCR/TV selection mode. That is, the VCR mode fixes third switch SW3 to contact "c" and fourth switch SW4 to contact "b" while the television mode fixes third switch SW3 to contact "b" and fourth switch SW4 to contact "c."
In a conventional VCR as described above, if a canal+ broadcast signal is received in the VCR mode of condition 3 with the canal+ position channel stored, second switch SW2 is connected to contact "e" so as to select the canal+ decoder output even if there is no canal+ decoder connected to the VCR. Therefore, there is no path to receive any broadcast signal. Moreover, the unscrambled canal+ broadcasting channel cannot be recorded.
Furthermore, if a canal+ broadcast signal is received in the television mode of condition 5, when a canal+ broadcast channel is selected after storing the canal+ position channel, the broadcast signal of the canal+ broadcasting channel cannot be received via the television's tuner without a canal+ decoder being connected to the VCR. Moreover, the unscrambled canal+ broadcast channel cannot be viewed on the television screen.
Meanwhile, U.S. Pat. No. 4,995,079 discloses a canal+ decoder switch circuit for a VCR, invented by the applicant of the present invention. Here, a normal picture can be viewed even without manually connecting a canal+ decoder to the television when a canal+ broadcast signal is received in a television mode.